In wireless communication systems, the communication needs of an access terminal are handled by an access network providing communication services for access terminals in a geographic area associated with the access network. The access terminal may also be referred to as a mobile station, user equipment, etc., and may be a wireless phone, wireless equipped computer, wireless equipped PDA, etc. Communication from the access network to the access terminal is referred to as forward or downlink communication. Communication from the access terminal to the access network is referred to as reverse or up link communication.
In code division multiple access (CDMA) communication systems, in addition to bearer traffic channels there are overhead channels that carry information used to facilitate use of the traffic channels. For example, in cdma2000 1x-EV-DO, there are five reverse link overhead channels: a pilot channel (PICH), a data rate control (DRC) channel, a data source control (DSC) channel, a reverse rate indication (RRI) channel, and an acknowledgement channel (ACK). The PICH provides channel estimation on the reverse link, and allows coherent demodulation of reverse link traffic channels. The DRC channel provides feedback from an access terminal regarding the forward link channel for use in management of forward link scheduling. For example, the DSC channel provides feedback for fast serving sector switching on the forward link. The RRI channel indicates the reverse link traffic channel data rate to expedite the decoding process. The ACK channel provides feedback to support forward link hybrid automatic retransmission requests (HARQ).
Because of this channel structure, the performance of forward link traffic channels is coupled with the performance of reverse link overhead channels. In other words, the accuracy and speed of the reverse link overhead channel feedback will influence the sector throughput on the forward link. Accordingly, it may be desirable to improve the speed and accuracy of the reverse link overhead channel feedback. Using the DRC channel as an example, a larger DRC channel power gain can often result in a faster and more accurate feedback, and may result in an improvement in the forward link capacity. By contrast, a smaller DRC channel gain produces a slower, less accurate feedback, and results in less forward link capacity. However, the tradeoff in having better reverse link overhead channel feedback is that more resource tends to be consumed.
For some symmetric, real-time, low data rate services such as Voice-Over-Internet-Protocol (VoIP), the overall system capacity may be reverse link limited rather than forward link limited. In these situations, improving the forward link capacity by increasing the reverse link overhead channel power gain does not improve the overall system capacity because it is the reverse link capacity that creates the bottleneck.